The art of detection of fluid flow is replete with different classifications of inventions indexed for different purposes, say based on type of use involved versus their principles of operation. While detection of change in flow of fluids (under flow/no-flow conditions) using transient heat transfer principles may have occurred, I am unaware of any detector or method which has cascaded the output effect to detect an ultrasmall change in flow conditions under a variety of occurrences, especially say from a heat sensing position completely exterior of the fluid-carrying body while maintaining the integrity of the interior of the body intact, i.e. without providing openings through the body itself.